Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in JAVA):

Solution:
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;

public class Main {
	void run() {
		Scanner sc = new Scanner(System.in);
		int h = sc.nextInt(), w = sc.nextInt();
		boolean[][] s = new boolean[h][w];
		int[][] d = new int[h][w];
		int countInitialBlack = 0;
		for (int i = 0; i < h; i++) {
			String str = sc.next();
			for (int j = 0; j < w; j++) {
				s[i][j] = str.charAt(j) == '.';
				d[i][j] = -1;
				if(!s[i][j]) {
					countInitialBlack++;
				}
			}
		}
		
		Queue<Point> queue = new LinkedList<>();
		Point start = new Point(0, 0);
		Point goal = new Point(h-1, w-1);
		int tmpX, tmpY;
		
		queue.offer(start);
		d[start.y][start.x] = 0;
		int[] dx = {1, 0, -1, 0}, dy = {0, 1, 0, -1};
		
		while(queue.size() > 0) {
			Point p = queue.poll();
			if(p.y == goal.y && p.x == goal.x) {
				break;
			}
			for(int i = 0; i < 4; i++) {
				tmpY = p.y + dy[i];
				tmpX = p.x + dx[i];
				
				if(0 <= tmpY && tmpY < h && 0 <= tmpX && tmpX < w 
						&& s[tmpY][tmpX] && d[tmpY][tmpX] == -1) {
					queue.offer(new Point(tmpY, tmpX));
					d[tmpY][tmpX] = d[p.y][p.x] + 1;
				}
					
			}
		}
		
		int minWhiteCell = d[h-1][w-1] + 1;
		if(d[h-1][w-1] != -1) {
			System.out.println(h * w - countInitialBlack - minWhiteCell);
		}else {
			System.out.println(-1);
		}
		
		sc.close();
	}

	void debug(Object... o) {
		System.out.println(Arrays.deepToString(o));
	}

	public static void main(String[] args) {
		new Main().run();
	}
}

class Point {
	int x;
	int y;
	public Point(int y, int x) {
		this.y = y;
		this.x = x;
	}
	
}